[Dependence of the character of EPSP summation in mollusk neurons on the level of the membrane potential].

The dependence of monosynaptic EPSP summation properties on the membrane potential level was studied in the experiments on identified neurons of mollusc Planorbis corneus. Summation functions were obtained by means of randomized paired stimuli technique. It was shown that the value of the interstimulus++ interval corresponding to the most marked EPSP interactions depended, mainly, on the postsynaptic mechanism. Really, selective changes in postsynaptic neuron parameters produced by changes in hyperpolarizing current led to a shift of the appropriate position of the summation function extremum. The results obtained made it possible to put forward the suggestion of selective (for every input or groups of inputs) "settlement" of neurons to specific intervals (frequencies); such "settlement" may be modulated by changes in the membrane potential in the corresponding part of a neuron. Possible functional role of this mechanism is discussed.